It has been known to provide various types of containers for use in the medical field for the sterilization and subsquent storage of medical instruments. Such prior containers have sought to solve recognized problems relating to a durable leak-proof construction, effective sterilization fluid transmission (i.e. gas or steam penetration), positive and tamper-effective securement of the case when in its closed position for storage and ready usage which assures that the contents of the case remain sterile until the case is opened. Also, there has been a need to improve the wire (metal) mesh basket unit which is detachably supported within the case for holding the instruments to be sterilized.